p2p: meter peer traffic, emit metered peer events (#17695)

This change extends the peer metrics collection:

- traces the life-cycle of the peers
- meters the peer traffic separately for every peer
- creates event feed for the peer events
- emits the peer events

p2p/server.go

@@ -864,7 +864,11 @@ func (srv *Server) listenLoop() {
 			}
 		}
 
-		fd = newMeteredConn(fd, true)
+		var ip net.IP
+		if tcp, ok := fd.RemoteAddr().(*net.TCPAddr); ok {
+			ip = tcp.IP
+		}
+		fd = newMeteredConn(fd, true, ip)
 		srv.log.Trace("Accepted connection", "addr", fd.RemoteAddr())
 		go func() {
 			srv.SetupConn(fd, inboundConn, nil)
@@ -917,6 +921,9 @@ func (srv *Server) setupConn(c *conn, flags connFlag, dialDest *enode.Node) erro
 	} else {
 		c.node = nodeFromConn(remotePubkey, c.fd)
 	}
+	if conn, ok := c.fd.(*meteredConn); ok {
+		conn.handshakeDone(c.node.ID())
+	}
 	clog := srv.log.New("id", c.node.ID(), "addr", c.fd.RemoteAddr(), "conn", c.flags)
 	err = srv.checkpoint(c, srv.posthandshake)
 	if err != nil {